effect of changing pH of paint?

[PaintByNumbers]

Liquitex makes a fantastic red/brown called Van Dyke Brown. Great for chestnut horses. But its only available as a thick tube paint, and its rheology stinks. Trying to thin it with water just makes it a less thick, gummy streaky paste.

 

I know that sometimes manufacturers use a thickener that depends on a slightly acidic pH, so I used a baking soda solution to thin this paint and it worked perfectly; the paint becomes a nice liquid.

 

But I don't know if this will degrade the film quality.

[drjsallison]

Baking soda (sodium carbonate) may leave a slight film of off color if not diluted enough. If you can find a little bit of potassium carbonate (I think you can get it at most drug stores for treating indigestion) you are less likely to have film issues. If there are no unwanted color variations then it is safe to say that the integrety of the paint (adhesion and all) are perfectly fine.

[airhead]

Have you tried reducing the paint with some flow improver or glaze medium?

 

Put a bit of the paint with a lot of reducer in a sealable container (old paint bottle or film can) add an aggitator and shake away.

 

Most tube acrylics require a bit of work to reduce to the levels that we can use.

[PaintByNumbers]

Additives won't get rid of the pasty nature of the paint. They add a chemical which reacts with the acrylic to make it pasty. You have to change the pH to reverse the chemical reaction.